JP2579458B2 - Anisotropic conductive film and method for producing the same - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an anisotropic conductive film and a method for producing the same.

[Prior art and its problems] With the miniaturization, thinning, and high definition of electronic devices, the density of various components including flat displays such as LCDs has increased, and it has been responding to the thinning of the connection parts with various wiring. The development of connection materials is strongly desired.

In response to this demand, recently, an anisotropic conductive film, which has electrical conductivity only in a desired fixed direction and exhibits electrical insulation in the other direction, has been used as a connection material between fine electrode patterns. It is attracting attention.

For example, an anisotropic conductive film (electronic material vo) formed by uniformly dispersing metal fine particles having a diameter of about 15 μm in a rubber film
l23, No. 7, P69-73 (1984)). For example, as shown in FIG. 5A, the anisotropic conductive film 5 is interposed between the electrode pattern 2 on the flexible printed board 1 and the electrode pattern 4 on the glass substrate 3, and a temperature of about 150 ° C. is applied. The connection between the two electrode patterns is achieved only by crimping while pressing. As the metal particles M in the anisotropic conductive film, a lead-tin (Pb-Sn) low melting point solder is used.
When heated, the metal particles are melted, and at the same time the rubber film is melted. When heated, the metal particles melt and spread, spread on the electrode pattern between the two substrates, and an electrical connection therebetween is achieved. On the other hand, the rubber extruded from between the electrodes by pressurization fills a space formed between adjacent electrodes by a step of each electrode. As a result, as shown in FIG. 5 (b), the packing density of the metal particles with respect to the volume of the rubber filling this space decreases, the insulation between adjacent electrodes increases, and the film has conductivity only in the thickness direction of the film. At the same time, connection is made in the other direction so as to maintain insulation. Therefore, it is reported that the electrode pattern formed at a density of about 5 lines / mm (here, the electrode width W ₁ = 100 μm) exhibits good resolution.

However, VLSIs (ultra large scale integrated circuits) often use high-definition multi-contact electrodes (10 / mm or more). For example, an electrode pattern of 20 lines / mm (electrode width W ₂ = 2
5 μm) When connecting the particles, conductive particles having a particle size of several μm order or less must be uniformly dispersed in the film. However, as shown in FIG. Problems such as short-circuiting between adjacent electrodes due to mixing of diameter particles (b) and poor connection due to absence of particles M (c) occur. It was difficult to connect with such an anisotropic conductive film.

The present invention has been made in view of the above circumstances, and has as its object to provide an anisotropic conductive film with high resolution and high reliability.

[Means for Solving the Problems] Therefore, in the anisotropic conductive film of the present invention, the conductive substance is formed as a pattern having regularity in a two-dimensional direction.

In the method for producing an anisotropic conductive film according to the present invention, a conductive film is formed on a substrate, and the conductive film is selectively removed so as to have a regular pattern at a desired pitch. Then, an insulating film is formed on the upper layer, the substrate is peeled off and removed, and finally, a protective film is applied to the exposed surface of the peeled anisotropic conductive film where the conductive substance is exposed.

[Operation] That is, when the anisotropic conductive film of the present invention is sandwiched between the electrode patterns of two substrates to be connected and heated and pressed, the insulating film has a two-dimensional regularity on the insulating film. The conductive patterns arranged on the substrate are heated and pressed to reduce the thickness of the insulating film and the protective film and extrude into the recesses between the electrodes. By forming a conductive path in the pattern, good electrical connection between the two substrates is enabled, and there is no short circuit between adjacent electrodes.

Further, the insulating film and the protective film function to bond between the substrates, and enable the bonding between the substrates simultaneously with the electrical connection.

Furthermore, the periphery of each conductive pattern is insulated by an insulating film and a protective film, which breaks the insulation only during use and shows conduction in the film thickness direction, and since the surface is covered with the protective film, Deterioration such as oxidation can be prevented. In other words, when selecting the material of the conductive pattern, it is not necessary to consider deterioration due to exposure to the outside world, and the range of material selection is increased.

Further, according to the method of the present invention, after a conductive film is formed on a substrate, a high-precision pattern is formed by photolithography etching or an etching method using electron beam lithography. In this case, a highly uniform and highly accurate conductive pattern can be formed. Therefore, a high-resolution anisotropic conductive film can be formed.

Examples Hereinafter, examples of the present invention will be described in detail with reference to the drawings.

FIG. 1 (a) is a cross-sectional view of this anisotropic conductive film (FIG. 1 (b) is a perspective view showing a pattern arrangement state).
As shown, and styrene - butadiene formed of a resin insulating vertical a ₁ = 2.5 [mu] m in the film 101, the horizontal a ₂ = 2.5 [mu] m, the thickness of a ₃ = a 2.5 [mu] m square nickel (Ni) pattern 102 is distance P = 2.5 μm, and are regularly and vertically arranged (105 is a protective film).

Next, a method for producing this anisotropic conductive film will be described.

First, as shown in FIG. 2A, a release agent (not shown) containing silicon as a main component is applied onto a glass substrate 100, and then subjected to a screen printing process and a baking process to form a film having a film thickness of 10%.
A nickel film 102 'of several μm is formed.

Next, as shown in FIG. 2B, a resist 103 is applied.

Thereafter, as shown in FIG.
(L) is selectively carried out through the substrate (exposure).

Subsequently, as shown in FIG. 2 (d), development is performed to form a resist pattern 103 '.

Then, as shown in FIG.
The nickel film 102 'is removed by a wet etching method via 103'.

Thereafter, as shown in FIG. 2 (f), the resist pattern 103 'is removed to obtain a nickel pattern 102.

Further, after applying a styrene-butadiene block copolymer to the upper layer, a curing process is performed to form a styrene-butadiene resin film 101 as shown in FIG. 2 (g).

Finally, the glass substrate 100 is physically peeled off and removed by a tensile force, and a protective film 105 is applied thereon, thereby completing the anisotropic conductive film of the embodiment of the present invention as shown in FIG. 1 (a).

20 anisotropic conductive films thus formed
When used for connection between two substrates 201 and 202 having an electrode pattern of 2 mm / mm, as shown in FIG. 3, the particle size distribution of the conductive material and the aggregation of particles do not occur in the anisotropic conductive film. Since the conductive material, that is, the nickel patterns 102 are regularly and uniformly arranged, a highly reliable connection can be made without occurrence of a connection failure or a short circuit for an adjacent electrode.

In the embodiment, glass is used as the substrate, but a metal, a silicone resin, a Teflon resin, or the like can be appropriately selected as needed. Among them, when a material having good releasability from a conductive substance such as a Teflon resin is used, it is not necessary to use a release agent.

Further, the conductive material is not limited to nickel formed by the thick film method, but may be a nickel film formed through a vacuum deposition process and a plating process, and further, gold, platinum, silver, copper, iron, and aluminum. Metals such as chromium, or solder, metal compounds such as indium tin oxide (ITO), inorganic substances such as conductive carbon, inorganic compounds, conductive organic compounds, conductive organic metal compounds, etc. From among them, an appropriate selection may be made according to the constituent material of the electrode pattern to be connected.

Furthermore, the pattern formation of the conductive material may be performed according to the required pattern accuracy, such as using an electron beam lithography method for forming a resist pattern, or using a dry etching method for etching, in addition to a normal photolithographic etching method. Therefore, it can be appropriately changed.

In addition, as for the insulating film, in addition to styrene-butadiene resin, phenol resin, urea resin, melamine resin, allyl resin, furan resin, polyester, epoxy resin, silicone resin, polyimide resin, polyurethane, Teflon resin, etc. Resin, polyethylene, polypropylene, polybutylene, polymethyl methacrylate, polystyrene, acrylonitrile-styrene resin,
Thermoplastic resins such as acrylonitrile-butadiene-styrene resin, vinyl resin, polyamide resin, polyester, polycarbonate, polyacetal, ionomer resin, polyether sulfon, polyphenyl oxide, polyphenylene null sulfide, polysulfone, and polyvinylidene fluoride (fluororesin); It can be appropriately selected from those having an insulation resistance of 10 ⁸ Ω or more, such as cellulose resins such as ethyl cellulose, cellulose acetate, cellulose propionate, and cellulose nitrate.

In addition, as shown in FIG.
The registration error of the electrode patterns 203 and 204 202, actual electrode spacing T ₀ may be smaller than the electrode spacing T.
Accordingly, as shown in FIG. 4B, the smaller one of the minimum electrode width W _min and the minimum electrode interval T _min of each electrode pattern is defined as A, and the anisotropic conductive film shown in FIG. with B <(1/4) a to the larger of the width B ₁ or spacing B ₂ of the conductive material pattern 102 when is B,
Even when an alignment error occurs between the substrates, a high-resolution connection can be ensured. Further, by adjusting the width B ₁ or spacing B ₂ of the conductive pattern, and controls the conductors presence rate per unit area, it is possible to adjust the electrical characteristics.

[Effects] As described above, according to the anisotropic conductive film of the present invention, a pattern of a conductive material having regularity in a two-dimensional direction is formed on an insulating film. Short-circuiting between adjacent electrodes due to aggregation of
It is possible to connect electrode patterns with a high resolution of 10 lines / mm or more without problems such as poor connection due to lack of a conductive substance.

Further, according to the method of the present invention, after forming a conductive film on the substrate, patterning, furthermore, an insulating film is applied to this upper layer, so as to remove the substrate,
It is possible to extremely easily form a high-resolution and highly reliable anisotropic conductive film.

[Brief description of the drawings]

FIG. 1 (a) is a cross-sectional view of an anisotropic conductive film of an embodiment of the present invention, FIG. 1 (b) is a perspective view showing an arrangement state of conductive material patterns in the film, and FIG. a) to (g) are manufacturing process diagrams of the anisotropic conductive film, FIG. 3 is a diagram showing a connection example using the anisotropic conductive film, and FIGS. 4 (a), (b) and (c). 5) shows the relationship between the alignment error between electrode patterns to be connected and the conductive material pattern of the anisotropic conductive film. FIGS. 5 (a) and 5 (b) show conventional anisotropic conductive films. FIG. 6 is an explanatory diagram showing a state before and after connection of an electrode pattern using the method shown in FIG. 6. FIG. 6 is a state diagram in a case where a conventional anisotropic conductive film is used to connect a multi-contact electrode with high definition. DESCRIPTION OF SYMBOLS 1 ... Printed circuit board, 2 ... Electrode pattern, 3 ... Glass substrate, 4 ... Electrode pattern, 5 ... Anisotropic conductive film, M
... metal particles, 100 ... glass substrate, 101 ... insulating film, 102 ... nickel pattern, 102 '... nickel film, 103 ... resist, 104 ... photomask, 105 ...
Protective film, 201, 202 ... substrate, 203, 204 ... electrode pattern.

 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-54-126281 (JP, A) JP-A-58-188076 (JP, A) JP-A-58-23174 (JP, A) JP-A-51- 44264 (JP, A) JP-A-60-101885 (JP, A) Electronic Materials Vol. 23 No. 7 P. 69-73 (1984)

Claims (5)

(57) [Claims] A conductive pattern regularly arranged in a two-dimensional direction; an insulating elastic member which covers one of the conductive pattern arrangement surfaces and is filled between the patterns; and the conductive pattern. A protective film that covers the entire other surface of the arrangement surface, wherein the elastic member and the protective film decrease in film thickness by heat and pressure, and in a thickness direction of the anisotropic conductive film through the conductive pattern. An anisotropic conductive film formed of a member forming a conduction path. 2. A conductive film forming step of forming a conductive film on a substrate surface, a conductive pattern forming step of selectively removing the conductive film while leaving the conductive film regular, and on and between the conductive pattern. An elastic member forming step of forming an insulating elastic member, a peeling step of peeling and removing the substrate, and a protective film forming step of forming a protective film so as to cover the surface of the conductive pattern exposed by the peeling. The elastic member and the protective film are formed of a member that reduces a film thickness by heat and pressure and forms a conductive path in a thickness direction of the anisotropic conductive film through the conductive pattern. Method for producing conductive conductive film. 3. The method according to claim 2, wherein said pattern forming step is a photolithographic etching step.
4. The method for producing an anisotropic conductive film according to claim 1. 4. The method for producing an anisotropic conductive film according to claim 2, wherein said substrate is a substrate having a release film formed on a surface thereof. 5. The method for producing an anisotropic conductive film according to claim 2, wherein said substrate is a tetrafluoroethylene substrate.